Soft-Chemistry Derived Advanced Phosphors for Smart Lighting Devices Based on Blue or UV LEDs

Abstract

This work deals with phosphors suitable for applications in a new generation of Hg-free lamps based on deep ultraviolet (DUV), ultraviolet (UV) and blue light emitting diodes (LEDs). First, two synthesis routes, solid state reaction and Pechini method, have been used for preparing an original red phosphor, Y 3 BO 6 :Eu 3+ . Phase purity was confirmed by XRD analysis for Pechini derived sample after washing the powder with an acidic solution while the synthesis dependence of the morphological and optical characteristics was evidenced by SEM analysis and photoluminescence respectively. Y 3 BO 6 :Eu 3+ powders derived from Pechini process exhibited high photoluminescence quantum efficiency upon excitation at wavelengths corresponding to afore mentioned sources, in comparison with commercial Y 2 O 3 :Eu 3+ red phosphor. Furthermore, the Pechini method was used for elaborating Y 3 BO 6 :Eu 3+ spray-coated thin film. Its structural and optical features were also investigated. Finally, colorimetric simulations have pointed out that Y 3 BO 6 :Eu 3+ could be efficiently combined with blue and green phosphors to produce white light from DUV LEDs. Regarding blue LEDs sources, a mixture constituted of Y 3 Al 5 O 12 :Ce 3+ and Y 3 Al 5 O 12 :Pr 3+ powders has been investigated and resulted in promising results for providing white light with suitable features for indoor or outdoor lighting.

Uniform colloidal spheres for RE3BO6 (RE = Eu‐Yb, Y) and excitation‐dependent luminescence of Y3BO6:Eu3+ red phosphor

“…RE 3 BO 6 is an important host for luminescence applications, and it always crystallizes in three different space groups, including P 2 1 / c (RE = La‐Nd) and C 2/ m , C 2, or C m (RE = Pm‐Yb, Y) . Comparing with REBO 3 and REB 3 O 6 , RE 3 BO 6 is the rare earth rich host with RE 3+ occupying a low‐symmetry site, which has aroused a considerable interest in recent years . For example, red emission intensity from Eu 3+ is much stronger when doped in Y 3 BO 6 lattice compared to YBO 3 .…”

“…Pradal et al reported that the Eu 3+ content in Y 3 BO 6 can be up to 20 mol%, and the Y 3 BO 6 :Eu‐PVP composites exhibited the characteristic red emission of Eu 3+ rather than orange‐red under UV light excitation, indicating that they are potential candidates for next generation white light emitting diodes (LEDs) . However, it is noticed that rare‐earth borates including RE 3 BO 6 were usually synthesized by typical solid‐state reactions at high temperatures or sol‐gel technology followed by calcination . Therefore, the final products are always characterized by large size, irregular shape, and significant aggregation.…”

“…3 Comparing with REBO 3 and REB 3 O 6 , RE 3 BO 6 is the rare earth rich host with RE 3+ occupying a low-symmetry site, which has aroused a considerable interest in recent years. [13][14][15][16][17] For example, red emission intensity from Eu 3+ is much stronger when doped in Y 3 BO 6 lattice compared to YBO 3 . 13 In fact, Y 3 BO 6 possesses various molecular formulas of Y 17.33 ( BO 6 , Y 3+ ions exist in both YO 7 and YO 8 polyhedrons and boron atoms exist in BO 4 and two different types of BO 3 structural units.…”

“…17 However, it is noticed that rare-earth borates including RE 3 BO 6 were usually synthesized by typical solid-state reactions at high temperatures or sol-gel technology followed by calcination. [13][14][15][16][17] Therefore, the final products are always characterized by large size, irregular shape, and significant aggregation. It is widely accepted that phosphor particles of spherical shape and uniform size are desirable in highdefinition displays to improve the resolution and the overall luminescent performance.…”

“…3 Comparing with REBO 3 and REB 3 O 6 , RE 3 BO 6 is the rare earth rich host with RE 3+ occupying a low-symmetry site, which has aroused a considerable interest in recent years. [13][14][15][16][17] For example, red emission intensity from Eu 3+ is much stronger when doped in Y 3 BO 6 lattice compared to YBO 3 . 13 In fact, Y 3 BO .…”